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Later this year - "A step change in Supercharging technology"

So I listened to the earnings call yesterday and Elon made some interesting comments about Supercharging, including the fact that they are going to have a fairly large announcement around "a step change in Supercharging technology." Just before he made this comment he also stated that they were working on improving the speed at which cars get charged. He then said that the original reason they reached out to the New York Times was around the announcement that will now come later in the year.

I am guessing that they will find a way to dramatically reduce the time it takes for the car to charge on a Supercharger.

So what's your guess for what the announcement will be?

P.S. - For those of you interested, Elon talks about the Supercharger network around minute 31 of the earnings call.

P.S.S. - I bought the stock today based on the earnings call and the 10% drop in the price

I am hoping/guessing this will involve a drop in charging time as well. After all, Tesla has got to keep up with the competition:

http://green.autoblog.com/2013/02/22/chreos-ev-wildly-overpromises-600-m...

@breading - yep, I'm sure if you can afford one you will be able to get 1MW service at your house, which is what you would need for a 10 minute charge.

Gee, that's only a 4000A service (at 240v). Piece of cake. I'm not sure what that Chreos press release was trying to do. They haven't even made a prototype car yet. 3 years out. Uh huh. And what price? And why, pray tell, does that car have such a huge hood?

Well, if they can imagine a car that gets 600 miles of charge in 10 minutes, I can go right along and pretend to get 1 MW service at my house just as easily.

If Tesla can get 150 miles of charge done in as little as 15-20 minutes, I will be thrilled. At least I will be when they finally put some of those super chargers across the Midwest.

I just hope Tesla is being honest with owners about how often they should be using a supercharger in terms of its effect on battery life...do any owners here know how Tesla is handling this?
I assume the more they try to make the superchargers charge cars faster the more overall battery life will suffer?

If I was Tesla and being 100% honest I wouldn't recommend the cars to anyone making frequent (more than once every two weeks) roadtrips involving superchargers AND I would not recommend the cars to anyone travelling more than 25,000 miles per year on average.
Anyone travelling more than this will be looking at a battery replacement in around 5 years. Any less than 5 years of normal operation and requiring an expensive battery change would be totally unacceptable to me.

If I was Tesla I would be asking customers about their driving habits. Mainly their average milage per year and how often they intend to use superchargers. This would help to avoid bad press for Tesla in the future as nobody could say they weren't aware of these issues.

I agree teddy.

I think there are some serious misconceptions regarding the SC use.

Then again, it may be that TM doesn't know for sure how much damage the SC use is causing.

@teddyg - would you make that recommendation if in fact the effect on battery life were less than many other factors? They do tell you that you are risking your battery longevity when you do a max-range charge, so why would you assume that they would hide damage from supercharging?

I don't know for the precise cells used by Tesla, but in general charging lithium batteries at around a 1C rate can be done with no noticeable difference from slower charge rates. 90kW is only slightly over 1C (C is the capacity of the battery, so charging an 85kWh battery at 85kW is 1C), so I would expect as long as you slow down at higher charge levels (which it does) there will be no damage.

Teddyg,

I don't agree. I'm sure Tesla is monitoring very closely the Super Charger's effect on the battery in all respects. If they are about to announce a step up in the Super Charger rate, I'm sure it will be because they have accumulated enough data to say it can be done without shortening the battery life more than what was already allowed.

And if your battery is gone after 5 years it won't cost you a cent, as it will still be under warranty.
8 years, 125,000 miles for 60 kWh, 8 years and unlimited miles for the 85 kwh.

Teddyg,

The Panasonic batteries used in Roadster were tested in conjunction with NASA program. The batteries used in Model S is next generation and are presumably more robust.

It was concluded that batteries will last 1000 full discharge cycles with approximately 20% degradation. For 85kWh battery this will conservatively translate into 265,000 miles life span at rated miles or 200,000 miles at average "real life" miles.

Above results are very conservative because in average everyday use batteries would be cycled between 90 and 65% of charge (for 50 miles/day commute), significantly extending battery life.

The reality is that battery, except for extreme cases will last for the lifetime of the car.

See quote and link below. Note that C/5 charge is 5 times higher than the charging used for the SC

"Preliminary cycle life and safety tests on the Panasonic
NCR18650 cells were performed at JSC. Initial ob
servations show capacity degradation of roughly
4.3 percent over 200 cycles at a C/5 charge and C/
10 discharge rate at room temperature."

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20110003627_2011001...

@vgrinshpun - Good stuff, thanks!

NASA article is for different charge rates.

C/10 = 0.10C

C/5 = 0.20C

We are talking here about multiples of C with Supercharger, not fractions of C.

As JAT points out, discharge is already demonstrated at 4C, so that's a pretty good indicator of the reasonable charging rate limit with this pack. My money is on 2-3C with the step change improvement.

I believe TM's testing data and conclusions about the safety of Supercharging to limited levels of State of Charge (50-70%).

TM has active temp control including heat elimination, so they can easily outperform a naked cell and protect its life much better.

Don't think you need to worry about using their Superchargers when they are fully warranting the use. Their software prevents harming the battery.

Mark,

Thanks for the correction.

Do you have any specific information or maybe an educated guess estimate on design lifespan of Model S battery (end of life capacity = 80%).

I find it strange that this information is so difficult to get. Panasonic got to test their batteries and I am sure that this information must be available internally.

Tesla must have performance specification for the batteries they are using...

Thanks

Gee, are you guys battery engineers? "If I were Tesla I would..." This IS the single most important part of the car and EV cars in general. Tesla has spent years developing their technology and the range and reliability results (see Roadster) show they are at the head of the class.

And even if you are battery engineers what projects have you developed that even approach what is under the floor of a Model S.
All I can say is wow...just wow. But this is the internet and everybody is an expert.

Well, in my humble opinion, TM has far and away the most advanced battery pack technology on the planet. Their team is second to none, and Boeing would have been lucky to get Elon's help.

And well yes, that opinion does come from an EE who runs a company full of engineers manufacturing hi volume electronics with Lithium Ion cells. So there is a reasonable basis for my opinion about TM.

Because of what some forum participants actually do know, we uniquely recognize just how brilliant team TM really is.

Example: Did you know that the waste heat developed in the motor is actually fed back into the battery pack to warm it up in cold weather? Per Elon, those heat pumps are managed by firmware to work in both directions. Never wasting a watt or a BTU. Do you know how cool that is? That is so elegant, it's sheer engineering artistry.

A thread like this is in fact about speculation, but it's usually more interesting when it's based on fairly well educated guesses.

Nissan recommends not fast charging the Leaf more than once per day on average (multiple times per day occasionally is ok). And that is with a 2C charge rate on a pack with no active cooling.

I wouldn't be worried about 1C charging a pack with cooling at all.

vgrinshpun - A bit OT, but if this non-engineer read the NASA report right, the specific energy the test cells output was reduced by about 10% from the base scenario of 20C (68F) to one of the test markers of 0C (32F). Good rule of thumb to know.

Wow, something useful came from the Border piece... A picture of the panels.

@teddy - what is the basis of your 25k per year limit? I expect to be right around there with my daily use of about 75 MPD duing weekdays and 50 MPD on non work days average. I figure I a right in the sweet spot for charging without max (will go to max several times a year for roadtrips but typically not) and not running it even close to the min. and I would save more in gas due to the higher miles. If the battery craps out after 5 years of this, I am fully covered. whats the downside?

joyrider - I think you are missing the point of this discussion while being a bit presumptive about the reasons you think some of us are engaging in it.

The design life of the battery is one of the major points that Tesla detractors are making against the Model S. With precious little information at their disposal they happily jump to the conclusion that since battery warranty is 8 years, one must include cost of it's replacement after 8 years while considering the lifetime costs of Model S. Than they throw the maximum cost of the replacement they perceive they can reasonably can get away with and victoriously declare the case closed - Model S lifetime costs are too high and the company will be toast because there will be no demand beyond early adopters.

However laughable this argument might sound to people on this forum, the common public perception is closely aligned with it. I am an electrical engineer, and while do not specialize in Lithium Ion batteries have a gut feeling that the battery in Model S, particularly 85kWh one, for all practical purposes will last the lifetime of the car under all except very extreme conditions.

I have the highest respect and admiration for Tesla Motors. Elon Musk is perhaps the most straight talking CEO ever, and I do not believe that he was kidding when he set to engineer, build, and mass produce the best car in the world. I am, however, not prepared to take my gut feeling about the lifespan of the battery as an article of faith (especially when Tesla Motors is not very vocal on this issue). I would like to have some specific independent information which can prove that my gut feeling about battery life is correct, if not for any other reason then to credibly counter the critics.

One last point - I believe that Tesla have multiple legitimate reasons to limit information about battery to the terms of their warranty and prepaid options for replacement. Having worked in various engineering organizations for a long time, however, I am quite certain that this is not because this information does not exist, it is because their battery management system is unique and relatively new. Perhaps the certainty they have about the data is not at the level they would be comfortable with to make data widely available.

@jkirkebo - the LEAF fast-charge is actually 1.6C -- 80% charge in 30 minutes and it does have active cooling but only air rather than liquid. But still, I agree with your point.

Vgrinspun - some other data points here.

My take as to why they limit their promises to the 8 year warranty is this:

Robust engineering is about lots of margin. So you under-promise and over-deliver.

If you can do X under good conditions, then you rate it at 0.5X so there is buffer for unforeseen hits, while still delivering good performance.

I have talked with Elon, JB, and other TM engineers, and these guys are honest to a fault, and sincerely on a mission to do this right. The numbers disussed as intrinsic to the battery are in the 10 - 20 year range, but it is so highly dependent on individual environmental and usage conditions that it would be irresponsible to set that expectation.

I don't think TM is hiding anything. They just want folks to expect safe, rather best case numbers.

Example - I get great battery life out of my iPhone. But here's a how thermal event affected that: one day my black glass iPhone unfortunately sat on my dash for an hour while the car was locked and in full sun. When I got back to it, it was so hot I could not hold it. I knew this was trouble. The silicon would be fine, but the Lithium Polymer cell in it would be compromised. Sure enough, it would no longer hold a charge and had to be replaced.

So when Apple quotes battery life they have to make some assumptions about how you will use it, and leave some margin. Unless you abuse it, it works great.

So if you want to baby your pack so it lasts longer than spec then do this:

1. Leave it plugged in when not in use. This lets the active thermal management run whenever it's needed.

2. Stay between 80 and 20 % charge. Extreme discharge or max charge has a cumulative effect on the chemistry and strucure (grows dendrites) and shortens life.

So don't leave your black car parked in the Arizona sun for a month with a discharged battery. (Duh!).

I you take good care of it, your pack will last longer than promised.

BOT - this thread is about Superchargers -

What do you guys think qualifies for a step change (big leap)?

I think getting a 50% refill in 10-15 minutes would make a huge difference. It'd feel more like gas stop.

I also think pushing the fill level cutoff for fast charging to say 70% would make a big difference. if TM can tease that out of the thermal and charge management system, that would be awesome.

Speed would multiply the user capacity, and fill level is like virtually upping the density of SC locations. Basically, you could go farther and faster with the stations they already have.

Of course, more stations is more convenient in all cases.

It took a decades to build the gasoline infrastructure. This change will blow that away. In 36 months, I think we will be "shocked" at how quickly things are changing.

jat: I've seen 46kW charge rates on the Leaf, that is very close to 2C. However the current ramps down at 50-60% SOC depending on temperature.

And there is no active air cooling for the Leafs battery. It is entirely passive.

I think this would be a game changer. The thing that concerns me, though, is cost if this would require adding 800kWh worth of batteries to every SC station. If one assumes $300 per kWh installed cost for the battery, that would add up to $240,000 per SC station or $24 MM per 100 SC stations.

vgrinshpun;
It's early days for this yet, but "used" batteries could be had for lots less and stacked as deep as needed to accommodate their reduced (70%?) capacity. Some analog of the thermal management system in the MS would likely be needed, of course.
IAC;
Mark K, jat, vgrinshpun +1,+1,+1
Thanks for the very informed commentary.

Net, net I stick with my projection that charging times will be halved, which as noted above at least doubles the throughput capacity of the S/C network. Not that I ever accepted that this was going to be a serious problem.

Vgrinshpun - Hopefully they can manage capital costs by phased introductions in high traffic areas first.

Also, fractional installs (with modules less than 800kH) may be just fine in lower traffic areas.

800kWh can handle 10-20 50% (85 / 60) charges in a burst with no recovery time. That sounds pretty good for a busier hub, but is probably overkill for less popular sites in the early days.

Long term, they'll probably need more than a megawatt-hour once EVs get popular.

In any case, I think they contemplate a scalable architecture, and they will have plenty of statistical data on their servers to find the sweet spot.

jat, jkirkebo, the LEAF battery has a different chemistry.

They are all called 'Lithium Ion', but in fact there is a widely differing palet of all kinds of batteries with varying properties (charge/discharge rates, energy density, tolerance to high/low temperatures, cycle life, calendar life, cost, etc.). The comparison with the LEAF battery is therefore not very meaningful.

As an addition, the specs for the Panasonic NCR18650 used in the model S state a maximum charge charge rate of 0.7 C: http://industrial.panasonic.com/www-data/pdf/ACA4000/ACA4000PE4.pdf

It would seem the current SuperChargers already exceed the official Panasonic specs, even more so when they put on a 'turbo'.

I haven't seen any commentary on the capacitance breakthrough Elon mentioned in either an article or interview. Could the SC announcement be related to this breakthrough?

@Andre-nl
That .7C charge rate is without cooling. The cooling system in the MS allows for quicker charging.


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